The systems developed by the air brake equipment industry to meet the Department of Transportation skid control requirements for semi-trailers and container chassis (FMVSS-121) consist basically of a number of pneumatic, electric and electropneumatic components.
A few of these, such as the (electric) sensors and the (pneumatic) spring brake chambers are sub-assembled with the axles; the other components must be mounted on the sprung part of the vehicle and interconnected by tubing, hoses and wiring to form the required pneumatic and electric system circuitry. The common practice is to mount the other components individually onto structural members of the trailer subframe respectively chassis. In this "scattered" type, installation, the actual location and positioning of the components is to a large extent controlled by the configuration and location of said structural members, which vary on different types of vehicles and in most cases, cannot be rearranged to suit the optimum requirements for mounting the skid control components.
Typical examples of the pneumatic components are air reservoirs, amplifying relay valves, check valves and pressure protection valves; typical electric components are computers (also known as "logic modules"), junction and fuse (or circuit breaker) boxes; typical electro-pneumatic components are the control valves. A considerable number of these components is required, particularly in a tandem axle vehicle. Installing them in place and making all air and electrical connections requires quite a number of additional man hours on the main assembly line at or after the finishing station. Some of the components, particularly the computers, are very compact and relatively expensive devices. They are, therefore, attractive objects for thieves.
Since they are mounted in an exposed position underneath the vehicle, these components and the air and electrical lines connecting them are splashed by water and mud and struck by road salt and road debris.
An object of this invention is to preassemble ("package") all skid control system components (other than those mounted on the axles) into a single unit which:
1. PROVIDES MECHNICAL PROTECTION FOR SYSTEM COMPONENTS FROM SUB-ASSEMBLY THROUGH INSTALLATION-UPON-VEHICLE STAGES AT THE MANUFACTURING PLANT;
2. PROVIDES ANTI-THEFT PROTECTION;
3. REDUCES "LINE TIME" (LABOR REQUIRED TO INSTALL SKID CONTROL SYSTEM ON TRAILERS AND/OR CHASSIS);
4. PROVIDES MECHANICAL AND ANTI-CORROSION PROTECTION FOR SYSTEM COMPONENTS (INCLUDING AIR PIPING AND ELECTRICAL WIRING) IN ROAD OPERATION;
5. DISCOURAGES THEFT OF VALUABLE SYSTEM COMPONENTS IN ROAD OPERATION;
6. MAKES IT POSSIBLE TO REMOVE THE COMPLETE SKID CONTROL SYSTEM AND REPLACE IT BY A SPARE UNIT IN MINIMUM TIME WITHOUT SPECIAL SKILLS OR TOOLS; AND
7. ACHIEVES THESE AIMS IN THE MOST ECONOMICAL WAY, WITHOUT CHANGES IN THE EXISTING DESIGN OF TRAILER AND CHASSIS FRAMES AND SUSPENSION COMPONENTS, OR COMPROMISING THE SYSTEM PERFORMANCE WHILE PERMITTING TROUBLE SHOOTING AND REPAIR OF THE SYSTEM WITHOUT REMOVING IT AS A UNIT FROM THE VEHICLE.